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Add 64-bit atomics

pull/9600/head
Kevin Bracey 2019-02-04 13:06:58 +02:00
parent 94f5646303
commit f8e3f5dc2c
3 changed files with 113 additions and 165 deletions
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25
UNITTESTS/stubs/mbed_critical_stub.c
View File

@ -103,6 +103,31 @@ uint32_t core_util_atomic_decr_u32(volatile uint32_t *valuePtr, uint32_t delta)
}
uint64_t core_util_atomic_load_u64(const volatile uint64_t *valuePtr)
{
return 0;
}
void core_util_atomic_store_u64(volatile uint64_t *valuePtr, uint64_t desiredValue)
{
}
bool core_util_atomic_cas_u64(volatile uint64_t *ptr, uint64_t *expectedCurrentValue, uint64_t desiredValue)
{
return false;
}
uint64_t core_util_atomic_incr_u64(volatile uint64_t *valuePtr, uint64_t delta)
{
return 0;
}
uint64_t core_util_atomic_decr_u64(volatile uint64_t *valuePtr, uint64_t delta)
{
return 0;
}
bool core_util_atomic_cas_ptr(void *volatile *ptr, void **expectedCurrentValue, void *desiredValue)
{
return false;

52
platform/mbed_critical.c
View File

@ -358,6 +358,58 @@ uint32_t core_util_atomic_decr_u32(volatile uint32_t *valuePtr, uint32_t delta)
#endif
/* No architecture we support has LDREXD/STREXD, so must always disable IRQs for 64-bit operations */
uint64_t core_util_atomic_load_u64(const volatile uint64_t *valuePtr)
{
core_util_critical_section_enter();
uint64_t currentValue = *valuePtr;
core_util_critical_section_exit();
return currentValue;
}
void core_util_atomic_store_u64(volatile uint64_t *valuePtr, uint64_t desiredValue)
{
core_util_critical_section_enter();
*valuePtr = desiredValue;
core_util_critical_section_exit();
}
bool core_util_atomic_cas_u64(volatile uint64_t *ptr, uint64_t *expectedCurrentValue, uint64_t desiredValue)
{
bool success;
uint64_t currentValue;
core_util_critical_section_enter();
currentValue = *ptr;
if (currentValue == *expectedCurrentValue) {
*ptr = desiredValue;
success = true;
} else {
*expectedCurrentValue = currentValue;
success = false;
}
core_util_critical_section_exit();
return success;
}
uint64_t core_util_atomic_incr_u64(volatile uint64_t *valuePtr, uint64_t delta)
{
uint64_t newValue;
core_util_critical_section_enter();
newValue = *valuePtr + delta;
*valuePtr = newValue;
core_util_critical_section_exit();
return newValue;
}
uint64_t core_util_atomic_decr_u64(volatile uint64_t *valuePtr, uint64_t delta)
{
uint64_t newValue;
core_util_critical_section_enter();
newValue = *valuePtr - delta;
*valuePtr = newValue;
core_util_critical_section_exit();
return newValue;
}
bool core_util_atomic_cas_ptr(void *volatile *ptr, void **expectedCurrentValue, void *desiredValue)
{

201
platform/mbed_critical.h
View File

@ -202,175 +202,16 @@ MBED_FORCEINLINE void core_util_atomic_flag_clear(volatile core_util_atomic_flag
*/
bool core_util_atomic_cas_u8(volatile uint8_t *ptr, uint8_t *expectedCurrentValue, uint8_t desiredValue);
/**
* Atomic compare and set. It compares the contents of a memory location to a
* given value and, only if they are the same, modifies the contents of that
* memory location to a given new value. This is done as a single atomic
* operation. The atomicity guarantees that the new value is calculated based on
* up-to-date information; if the value had been updated by another thread in
* the meantime, the write would fail due to a mismatched expectedCurrentValue.
*
* Refer to https://en.wikipedia.org/wiki/Compare-and-set [which may redirect
* you to the article on compare-and swap].
*
* @param ptr The target memory location.
* @param[in,out] expectedCurrentValue A pointer to some location holding the
* expected current value of the data being set atomically.
* The computed 'desiredValue' should be a function of this current value.
* @note: This is an in-out parameter. In the
* failure case of atomic_cas (where the
* destination isn't set), the pointee of expectedCurrentValue is
* updated with the current value.
* @param[in] desiredValue The new value computed based on '*expectedCurrentValue'.
*
* @return true if the memory location was atomically
* updated with the desired value (after verifying
* that it contained the expectedCurrentValue),
* false otherwise. In the failure case,
* exepctedCurrentValue is updated with the new
* value of the target memory location.
*
* pseudocode:
* function cas(p : pointer to int, old : pointer to int, new : int) returns bool {
* if *p != *old {
* *old = *p
* return false
* }
* *p = new
* return true
* }
*
* @note: In the failure case (where the destination isn't set), the value
* pointed to by expectedCurrentValue is instead updated with the current value.
* This property helps writing concise code for the following incr:
*
* function incr(p : pointer to int, a : int) returns int {
* done = false
* value = *p // This fetch operation need not be atomic.
* while not done {
* done = atomic_cas(p, &value, value + a) // *value gets updated automatically until success
* }
* return value + a
* }
*
* @note: This corresponds to the C11 "atomic_compare_exchange_strong" - it
* always succeeds if the current value is expected, as per the pseudocode
* above; it will not spuriously fail as "atomic_compare_exchange_weak" may.
*/
/** \copydoc core_util_atomic_cas_u8 */
bool core_util_atomic_cas_u16(volatile uint16_t *ptr, uint16_t *expectedCurrentValue, uint16_t desiredValue);
/**
* Atomic compare and set. It compares the contents of a memory location to a
* given value and, only if they are the same, modifies the contents of that
* memory location to a given new value. This is done as a single atomic
* operation. The atomicity guarantees that the new value is calculated based on
* up-to-date information; if the value had been updated by another thread in
* the meantime, the write would fail due to a mismatched expectedCurrentValue.
*
* Refer to https://en.wikipedia.org/wiki/Compare-and-set [which may redirect
* you to the article on compare-and swap].
*
* @param ptr The target memory location.
* @param[in,out] expectedCurrentValue A pointer to some location holding the
* expected current value of the data being set atomically.
* The computed 'desiredValue' should be a function of this current value.
* @note: This is an in-out parameter. In the
* failure case of atomic_cas (where the
* destination isn't set), the pointee of expectedCurrentValue is
* updated with the current value.
* @param[in] desiredValue The new value computed based on '*expectedCurrentValue'.
*
* @return true if the memory location was atomically
* updated with the desired value (after verifying
* that it contained the expectedCurrentValue),
* false otherwise. In the failure case,
* exepctedCurrentValue is updated with the new
* value of the target memory location.
*
* pseudocode:
* function cas(p : pointer to int, old : pointer to int, new : int) returns bool {
* if *p != *old {
* *old = *p
* return false
* }
* *p = new
* return true
* }
*
* @note: In the failure case (where the destination isn't set), the value
* pointed to by expectedCurrentValue is instead updated with the current value.
* This property helps writing concise code for the following incr:
*
* function incr(p : pointer to int, a : int) returns int {
* done = false
* value = *p // This fetch operation need not be atomic.
* while not done {
* done = atomic_cas(p, &value, value + a) // *value gets updated automatically until success
* }
* return value + a
*
* @note: This corresponds to the C11 "atomic_compare_exchange_strong" - it
* always succeeds if the current value is expected, as per the pseudocode
* above; it will not spuriously fail as "atomic_compare_exchange_weak" may.
* }
*/
/** \copydoc core_util_atomic_cas_u8 */
bool core_util_atomic_cas_u32(volatile uint32_t *ptr, uint32_t *expectedCurrentValue, uint32_t desiredValue);
/**
* Atomic compare and set. It compares the contents of a memory location to a
* given value and, only if they are the same, modifies the contents of that
* memory location to a given new value. This is done as a single atomic
* operation. The atomicity guarantees that the new value is calculated based on
* up-to-date information; if the value had been updated by another thread in
* the meantime, the write would fail due to a mismatched expectedCurrentValue.
*
* Refer to https://en.wikipedia.org/wiki/Compare-and-set [which may redirect
* you to the article on compare-and swap].
*
* @param ptr The target memory location.
* @param[in,out] expectedCurrentValue A pointer to some location holding the
* expected current value of the data being set atomically.
* The computed 'desiredValue' should be a function of this current value.
* @note: This is an in-out parameter. In the
* failure case of atomic_cas (where the
* destination isn't set), the pointee of expectedCurrentValue is
* updated with the current value.
* @param[in] desiredValue The new value computed based on '*expectedCurrentValue'.
*
* @return true if the memory location was atomically
* updated with the desired value (after verifying
* that it contained the expectedCurrentValue),
* false otherwise. In the failure case,
* exepctedCurrentValue is updated with the new
* value of the target memory location.
*
* pseudocode:
* function cas(p : pointer to int, old : pointer to int, new : int) returns bool {
* if *p != *old {
* *old = *p
* return false
* }
* *p = new
* return true
* }
*
* @note: In the failure case (where the destination isn't set), the value
* pointed to by expectedCurrentValue is instead updated with the current value.
* This property helps writing concise code for the following incr:
*
* function incr(p : pointer to int, a : int) returns int {
* done = false
* value = *p // This fetch operation need not be atomic.
* while not done {
* done = atomic_cas(p, &value, value + a) // *value gets updated automatically until success
* }
* return value + a
* }
*
* @note: This corresponds to the C11 "atomic_compare_exchange_strong" - it
* always succeeds if the current value is expected, as per the pseudocode
* above; it will not spuriously fail as "atomic_compare_exchange_weak" may.
*/
/** \copydoc core_util_atomic_cas_u8 */
bool core_util_atomic_cas_u64(volatile uint64_t *ptr, uint64_t *expectedCurrentValue, uint64_t desiredValue);
/** \copydoc core_util_atomic_cas_u8 */
bool core_util_atomic_cas_ptr(void *volatile *ptr, void **expectedCurrentValue, void *desiredValue);
/**
@ -409,6 +250,13 @@ MBED_FORCEINLINE uint32_t core_util_atomic_load_u32(const volatile uint32_t *val
return value;
}
/**
* Atomic load.
* @param valuePtr Target memory location.
* @return The loaded value.
*/
uint64_t core_util_atomic_load_u64(const volatile uint64_t *valuePtr);
/**
* Atomic load.
* @param valuePtr Target memory location.
@ -457,6 +305,13 @@ MBED_FORCEINLINE void core_util_atomic_store_u32(volatile uint32_t *valuePtr, ui
MBED_BARRIER();
}
/**
* Atomic store.
* @param valuePtr Target memory location.
* @param desiredValue The value to store.
*/
void core_util_atomic_store_u64(volatile uint64_t *valuePtr, uint64_t desiredValue);
/**
* Atomic store.
* @param valuePtr Target memory location.
@ -493,6 +348,14 @@ uint16_t core_util_atomic_incr_u16(volatile uint16_t *valuePtr, uint16_t delta);
*/
uint32_t core_util_atomic_incr_u32(volatile uint32_t *valuePtr, uint32_t delta);
/**
* Atomic increment.
* @param valuePtr Target memory location being incremented.
* @param delta The amount being incremented.
* @return The new incremented value.
*/
uint64_t core_util_atomic_incr_u64(volatile uint64_t *valuePtr, uint64_t delta);
/**
* Atomic increment.
* @param valuePtr Target memory location being incremented.
@ -528,6 +391,14 @@ uint16_t core_util_atomic_decr_u16(volatile uint16_t *valuePtr, uint16_t delta);
*/
uint32_t core_util_atomic_decr_u32(volatile uint32_t *valuePtr, uint32_t delta);
/**
* Atomic decrement.
* @param valuePtr Target memory location being decremented.
* @param delta The amount being decremented.
* @return The new decremented value.
*/
uint64_t core_util_atomic_decr_u64(volatile uint64_t *valuePtr, uint64_t delta);
/**
* Atomic decrement.
* @param valuePtr Target memory location being decremented.